But to answer your question "who cares?", hams care, and I'd be surprised if people sending encrypted transmissions are not soon discovered - and if you knowingly violate the regulations, you run the risk of losing your ham license. If you're not licensed, (or even if you are for egregious or repeat violators), there are various enforcement actions the FCC can take including significant fines, equipment confiscation, and other criminal penalties.
In my experience, there absolutely are plenty of hams out there who will triangulate you and report you for violations. You'd probably get away with a warning at first, to be fair, but many hams (at least around these parts) are old retired dudes with nothing better to do.
If you think I'm wrong, just walk around any ham fest and ask for help setting up your Winlink node ;-).
That being said these bands are out there for the public to use, the government has set aside a pretty decent portion of the available usable frequencies for use of the public. In my opinion is just in poor taste to not follow the rules here.
In these days when you can get a Baofeng HT for $25, there are already all sorts of unlicensed people stomping all over others just to be jerks.
And I wouldn't. Not trying to be an arse here... but more importantly, who cares? Someone has to discover whats happening and actually care that a rule is being violated. There really are not many hams that have the skill to figure out what is happening when they hear this on their precious 70cm band and THEN realize encryption is happening on top of the network layer. Sure, they exist, but they are also generally busy doing real things that matter rather than volunteering for the Amateur Auxiliary.
Queue: the relentless flood of pitch forks that "CRYPTION IS AGAINST THE RULE OF LAW ON MY HAM BANDS".